SEAL COVE — Po and Bear are the mushroom dogs. Well, they’re not really the mushroom dogs, they’re the keep-the-squirrels-away dogs. And mostly it’s little Po who does all the work, despite Bear’s greater stature.

“She has a big job this year,” said Dominika DelMastro, pointing to a nearby treetop, “because there’s a squirrel nest up there.”

Dominika is standing with her husband, John, on a path that winds its way from their house in the Tremont village of Seal Cove over some bog bridging, through a marshy patch and into a forest filled with straight, looming pines.

John plugs the holes with a Styrofoam cap to keep other spores from entering and growing.

It’s a bit reminiscent of a fairy land: patches of trees have been cleared, and in their place are stacks of short logs dotted with small round white patches. Some of the logs are leaning, A-frame style; others are stacked like a log cabin about waist high.

Every one is labeled with a piece of bright flagging tape bearing a date and a whimsical-sounding name: Golden Oyster, Lion’s Mane, Jupiter, Snow Cap.

Look a bit closer and you’ll see that some of the logs are covered, rather than white spots, in rings and rings of small brown mushrooms.

“The mushroom place is probably my idea field of work,” says Dominika, plucking a massive Shiitake from one of the logs. This one won’t go to the market, she explains, despite its impressive size. Its cap has flattened out — they’re best when the caps still curl slightly down.

Dominika and John have only been in the mushroom-growing business for around four years, six if you count the two years they spent experimenting. Despite the tidy and well-organized appearance of the mushroom farm now, it wasn’t a seamless process.

Neither one had commercial gardening or farming experience (John works for Acadia National Park and Dominika worked at College of The Atlantic) “We inoculated 100 logs,” laughs Dominika, “and nothing happened.”

But in the four years since, the couple have found a rhythm, and discovered that they can, indeed, get mushrooms to fruit.

The process begins not with mushrooms but with trees, which John harvests from a friend’s property nearby and cuts into manageable sections.

Shiitake growing on a log. Once inoculated, a log will continuously produce mushrooms until it is spent of glucose, the fuel they need to grow.

“Oaks are the best for Shiitake,” he explains. “Unfortunately where I cut is mostly Red Maple. That’s a B-level log for growing Shiitake mushrooms.”

“Oak, they’re very hardwood,” chimes in Dominika. “You, as a consumer, you’re not going to taste the difference. It’s a difference for the grower, because they will last longer. An oak log can produce for four, five, six years. But a maple log, it’s up to three years. The harder the wood the better it is.”

Logs only last so long, says John, before they rot, a process that is accelerated by the mushroom’s growth: because they aren’t plants and don’t photosynthesize, mushrooms need a source of glucose.

“That’s what they’re taking from the tree, the glucose,” says John, “because they don’t make their own. They will keep producing until a log is spent of glucose.”

Once the logs have been cut and holes drilled at intervals along their sides, it’s time for inoculation. “We haven’t inoculated in months,” says Dominika joyfully, as John begins to drill.

The DelMastros use an angle grinder with an adapter and a high-speed bit to fill the holes with “spawn,” a mix of sawdust (or any other substrate, says Dominika) and mycelium, a mass of branching, thread-like white hyphae that will eventually allow the fungus to sprout its fruit, the mushroom.

“Mycelium comes from spores,” Dominika explains, which are what the mushroom uses to reproduce. “A spore, when it encounters a moist environment, an environment it likes, it’s going to divide into chains of hyphae, when two of those chains meet they create the mycelium.”

Mycelia organisms can be massive (the largest known organism in the world is a 2,385 acre mycelia in Oregon, aptly nicknamed the Humongous Fungus). They’re also everywhere, helping trees communicate, says Dominka (and occasionally killing them off by feeding on their roots).

“A mushroom is just the fruit of a plant,” adds John. “The plant is called mycelium. It’s the stringy stuff you see underneath.”

The final step in the inoculation process is to seal the hole, now filled with spawn.

Po, an Australian shepherd mix, chases hungry squirrels out of the mushroom field.

“We need to seal the holes up with something so no other type of spore infects it,” says John. “We use Styrofoam caps” (the white spots a visitor will see on the logs that have not yet fruited).

“Once you have it inoculated, you put it in the wheelbarrow,” says John. “We’re very…what’s the word? Very carbon-neutral,” he laughs.

But mushrooms, particularly the couple’s favorite, shiitake, are finicky, especially when grown outside. They don’t like wind of any kind, too much sun, frost or low humidity, but too much water is a problem. There also are slugs and hungry squirrels to contend with, particularly in spring, when shiitake fruit and squirrels are hungry after a long winter.

So getting a viable commercial crop to sell at the market is difficult, particularly in the summer, when farmers markets abound.

That’s in part because, to get shiitake to fruit in the summer, “You have to trick them into thinking it’s spring or fall, because in the springtime and fall they just fruit naturally,” says Dominika. To do that, she puts the logs in an ice water bath each night and removes them during the day.

“They think it’s spring and they fruit,” she says, smiling.

The couple also recently built a small greenhouse to help extend the season.

It would be easier to grow mushrooms indoors, of course, with more control over the variables. But mushrooms grown indoors don’t have the same health benefits, says Dominika. “When grown outdoors they’re full of vitamin D.” They also have a better taste and texture, more woodsy, and they sear like meat.

The couple know that mushrooms aren’t for everyone. “People either love them or they hate them,” says Dominika. Branching out — into mushroom powders, seasonings and other items — would also help ease the strain of the winter months.

“We’re in the process of thinking about other products to help us during the wintertime,” says John. “Bringing it from a hobby to a viable business has been tough.”

You can find Middle Earth Mushrooms at farmers markets around the region, including in Bar Harbor, Northeast Harbor and Blue Hill.